CN111801839A - Electrode assembly having insulating film, method of manufacturing the same, and lithium secondary battery including the same - Google Patents

Electrode assembly having insulating film, method of manufacturing the same, and lithium secondary battery including the same Download PDF

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Publication number
CN111801839A
CN111801839A CN202080001682.1A CN202080001682A CN111801839A CN 111801839 A CN111801839 A CN 111801839A CN 202080001682 A CN202080001682 A CN 202080001682A CN 111801839 A CN111801839 A CN 111801839A
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electrode
insulating film
inorganic particles
electrode assembly
organic
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尹泫雄
河会珍
尹钟建
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LG Energy Solution Ltd
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LG Chem Ltd
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Priority claimed from PCT/KR2020/001508 external-priority patent/WO2020159296A1/en
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    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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    • Y02E60/10—Energy storage using batteries
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Abstract

The present invention relates to an electrode assembly for a lithium secondary battery, which includes an electrode, a separator, and a counter electrode, wherein an insulating film is formed on the entire surface of one or both sides of the electrode, and the insulating film is an organic-inorganic hybrid film containing inorganic particles and a binder polymer. The present invention also relates to a method of manufacturing the electrode assembly and a lithium secondary battery including the same.

Description

Electrode assembly having insulating film, method of manufacturing the same, and lithium secondary battery including the same
Technical Field
The present application claims the benefit of korean patent application No. 10-2019-.
The present invention relates to an electrode assembly including an insulating film, a method of manufacturing the same, and a lithium secondary battery including the same.
Background
With the rapid increase in the use of fossil fuels, there is an increasing demand for the use of alternative or clean energy. As part of this trend, most of the active research work has focused on the field of power generation and storage using electrochemistry.
Now, typical examples of electrochemical elements using such electrochemical energy include secondary batteries, and their use has been gradually expanded in a wide range of fields.
In recent years, with the progress and increase in demand for technical development of portable devices such as portable computers, portable telephones, cameras, and the like, the demand for secondary batteries as energy sources has also rapidly increased. Among these secondary batteries, many studies have been made on lithium secondary batteries that are environmentally friendly and exhibit high charge and discharge characteristics and long-life characteristics. In addition, such lithium secondary batteries have been commercialized and widely used.
The electrode assembly built in the battery case is a power generation element capable of charging and discharging, which has a stacked structure of a cathode, a separator, and an anode. The electrode assembly is classified into: a gel roll type in which a separator is interposed between a long sheet type positive electrode and a negative electrode having an active material applied thereto, and then they are all wound together; a stack type in which a plurality of positive electrodes and negative electrodes having a predetermined size are sequentially stacked with a separator interposed therebetween; a combination of the above types, i.e., a stack/folding type in which a bi-cell (bi-cell) or a full cell including a cathode, an anode and a separator is wound into a long sheet-type separator; and a stacking/stacking type in which bicells or full cells are sequentially stacked and stacked.
Meanwhile, a lithium secondary battery generally has a structure in which a non-aqueous electrolyte is impregnated into an electrode assembly including a cathode, an anode, and a porous separator. In general, a positive electrode is manufactured by coating a positive electrode mixture containing a positive electrode active material onto an aluminum foil, and a negative electrode is manufactured by coating a negative electrode mixture containing a negative electrode active material onto a copper foil.
Generally, the positive electrode active material is a lithium transition metal oxide, and the negative electrode active material is a carbon-based material. Recently, however, lithium metal batteries using lithium metal itself as a negative active material have been commercialized. In addition, research on a lithium-free battery, which uses only a current collector as an anode in manufacturing and then receives lithium from a cathode by discharging to use lithium metal as an anode active material, has been actively conducted.
Meanwhile, such a lithium secondary battery has a risk of causing a short circuit due to contact between a cathode and an anode when exposed to high temperature. Further, if a large amount of current flows in a short time due to overcharge, internal/external short circuit, local compression, etc., there is a risk of ignition/explosion when the battery is heated due to an exothermic reaction.
In addition, as charging and discharging are repeated, gas generated by a side reaction between the electrode material and the electrolyte solution not only expands the volume of the secondary battery, but also causes safety problems such as explosion.
In particular, in the case of a lithium metal battery using lithium metal as a negative electrode active material, dendrite growth occurs as charging and discharging are repeated. As the deterioration progresses to some extent, the dendrite falls off, then flows together with the electrolyte, and then flows out from the poorly joined portion of the separator. This detached dendrite then contacts the positive electrode, causing a short circuit. In addition, as the dendrite grows, it penetrates the separator and comes into contact with the positive electrode, which results in a loss of electrochemical performance.
To solve this phenomenon, an insulating tape is attached to the electrode tab to prevent a short circuit with the counter electrode. Alternatively, it has been attempted to prevent short circuits between electrodes by forming an organic-inorganic hybrid coating layer on a separator, thereby preventing the separator from shrinking due to heat.
However, this phenomenon does not occur only in the tab portion, and the use of such an insulating tape only solves the short-circuit problem, and is still insufficient to satisfy the requirement of securing the safety of the battery affected by overcharge, electrolyte side reactions, and lithium dendrite growth. The formation of an organic-inorganic hybrid coating also does not effectively solve the problem.
Therefore, there is still a high necessity for a structure capable of effectively securing the safety of the battery by solving the above-mentioned problems.
Disclosure of Invention
Technical problem
Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art and the technical objects requested in the past.
Specifically, the present invention provides an electrode assembly having a structure in which an organic-inorganic hybrid composition containing inorganic particles and a binder polymer is formed on the entire electrode surface in the form of an insulating film to effectively prevent short circuits with a counter electrode, which may be caused by various causes, and a method of manufacturing the same.
The present invention also provides an electrode assembly capable of preventing a capacity from being reduced while preventing the above-described short circuit even when an insulating film is included on the entire electrode surface, and a lithium secondary battery including the same.
In addition, the present invention provides an electrode assembly and a lithium secondary battery including the same, having needle-punching safety by using an insulating film containing specific inorganic particles when using an electrode containing CNT, which is a conductive material.
Technical scheme
According to an embodiment of the present invention, there is provided an electrode assembly for a lithium secondary battery including an electrode, a separator, and a counter electrode, wherein an insulating film is formed on the entire surface of one or both sides of the electrode, and the insulating film is an organic-inorganic hybrid film containing inorganic particles and a binder polymer.
In addition, the electrode includes a tab extending from a current collector, and the insulating film is further formed on the tab.
In this case, the insulating film formed on the tab may be formed on a portion of the tab other than the portion connected to the external terminal.
Here, a tab extending from the current collector may be coupled to the current collector by welding, and may be stamped in a form extending from the current collector at the time of electrode stamping.
Since the insulating film of the present invention is formed on the entire surface of the electrode, the movement of lithium ions due to the charge and discharge of the electrode should not be suppressed.
Accordingly, the insulating film may be an organic-inorganic hybrid film containing inorganic particles and a binder polymer in order to ensure mobility of lithium ions. Since the organic-inorganic hybrid film has better lithium ion mobility than the separator, even if formed on the entire surface of the electrode, it is possible to suppress the reduction of the battery capacity and output performance.
The binder polymer is not limited as long as it does not cause a side reaction with the electrolyte. In particular, however, the binder polymer used may be a polymer having a glass transition temperature (Tg) as low as possible, preferably from-200 ℃ to 200 ℃. This is because such a binder polymer can improve the mechanical properties of the final insulating film.
Further, the binder polymer does not need to have ion conductivity, but it is more preferable to use a polymer having ion conductivity. It is preferable from the viewpoint of capacity that the insulating film covers a part of the electrode, since lithium ions of the active material move in the covered portion.
Therefore, it is preferable that the binder polymer has a high dielectric constant. In fact, the degree of dissociation of the salt in the electrolyte depends on the dielectric constant of the electrolytic solvent. As the dielectric constant of the polymer increases, the degree of dissociation of the salt in the electrolyte may be improved. The dielectric constant of the polymer used may be 1 or more, particularly in the range of 1.0 to 100 (measurement frequency ═ 1kHz), preferably 10 or more.
In addition to the above functions, the binder polymer may have the following characteristics: gelated when immersed in a liquid electrolyte to exhibit a high swelling degree of the electrolyte. In fact, if the binder polymer is a polymer having an excellent swelling degree of the electrolyte, the electrolyte injected after the battery is assembled permeates the polymer, and the polymer that keeps absorbing the electrolyte becomes ion conductive to the electrolyte. Thus, the solubility coefficient of the polymer is preferably, if possible, from 15 to 45MPa1/2More preferably 15 to 25MPa1/2And 30 to 45MPa1/2. If the solubility coefficient is less than 15MPa1/2And greater than 45MPa1/2It is difficult for the conventional battery to swell with the liquid electrolyte.
Examples of such binder polymers include, but are not limited to, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-vinyl acetate copolymer, polyethylene oxide, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullan, cyanoethylpolyvinyl alcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide, mixtures thereof, and the like. Any materials may be used alone or in combination as long as they include the above-described characteristics.
Meanwhile, the inorganic particles, another component forming the insulating film, can form voids between the inorganic particles, play a role of forming fine pores, and also serve as spacers capable of maintaining a physical form. In addition, the inorganic particles have a feature that physical properties do not change even at a high temperature of 200 ℃, and thus the formed organic-inorganic hybrid layer becomes excellent in heat resistance.
The inorganic particles are not particularly limited as long as they are electrochemically stable. In other words, the inorganic particle useful in the present invention is not particularly limited as long as it does not cause oxidation and/or reduction reactions in the operating voltage range of the battery to be applied (e.g., 0 to 5V, based on Li/Li +). In particular, in the case of using inorganic particles having ion transfer ability, ion conductivity in an electrochemical element can be increased to improve performance, and therefore inorganic particles having high ion conductivity are preferable. Further, if the inorganic particles have a high density, it is difficult to disperse such particles during the production process, and there is a problem of weight increase in producing a battery. Thus, inorganic particles having a small density are preferred, if possible. In addition, an inorganic material having a high dielectric constant contributes to increase of the dissociation degree of an electrolyte salt such as a lithium salt in a liquid electrolyte to improve the ionic conductance of the electrolytic solution. Finally, if the inorganic particles have thermal conductivity, the heat absorbing ability is excellent, so that the thermal runaway phenomenon due to the formation of hot spots by local concentration of heat can be suppressed.
For the above reasons, it is preferable that the inorganic particles are (a) high dielectric inorganic particles having a dielectric constant of 1 or more, 5 or more, preferably 10 or more, (b) inorganic particles having piezoelectricity, (c) thermally conductive inorganic particles, (d) inorganic particles having lithium ion transferring ability, or a mixture thereof.
The inorganic particles having piezoelectricity are materials which are nonconductors under atmospheric pressure but have chargeability due to a change in internal structure when a certain pressure is applied. Such inorganic particles exhibit high dielectric characteristics in which the dielectric constant is 100 or more. When such inorganic particles are elongated or compressed by applying a certain pressure, electric charges are generated to charge one side positively and the other side negatively, respectively. Such particles are therefore materials having the function of generating a potential difference between the two sides.
If the inorganic particles having the above-described characteristics are used as a component of the insulating film, the particles can not only prevent the electrodes from being in direct contact due to external impact or dendrite growth, but also generate a potential difference within the particles upon external impact due to the piezoelectricity of the inorganic particles. Therefore, electron transfer, i.e., a flow of a minute current, occurs between the two electrodes to achieve a gradual decrease in the battery voltage, thereby improving safety.
Examples of the inorganic particles having piezoelectricity include BaTiO3、Pb(Zr,Ti)O3(PZT)、Pb1-xLaxZr1-yTiyO3(PLZT)、PB(Mg3Nb2/3)O3-PbTiO3(PMN-PT), hafnium oxide (HfO)2) Mixtures thereof, and the like, but are not limited thereto.
The inorganic particles having lithium ion transferring ability refer to inorganic particles having a function of accommodating lithium element but moving lithium ions without storing lithium. The inorganic particles having lithium ion transferring ability can transfer and move lithium ions due to a defect existing inside the particle structure. Therefore, such particles can prevent a decrease in lithium mobility caused by the formation of an insulating film, thereby preventing a decrease in battery capacity.
Examples of the inorganic particles having lithium ion transferring ability include: (LiAlTiP)xOyBase glass (0)<x<4,0<y<13) For example lithium phosphate (Li)3PO4) Lithium titanium phosphate (Li)xTiy(PO4)3,0<x<2,0<y<3) Lithium aluminum titanium phosphate (Li)xAlyTiz(PO4)3,0<x<2,0<y<1,0<z<3)、14Li2O-9Al2O3-38TiO2-39P2O5Etc.; lithium germanium thiophosphate (Li)xGeyPzSw,0<x<4,0<y<1,0<z<1,0<w<5) For example, lanthanum lithium titanate (Li)xLayTiO3,0<x<2,0<y<3)、Li3.25Ge0.25P0.75S4Etc.; lithium nitride (Li)xNy,0<x<4,0<y<2) Example ofSuch as Li3N, etc.; SiS2Base glass (Li)xSiySz,0<x<3,0<y<2,0<z<4) E.g. Li3PO4-Li2S-SiS2Etc.; p2S5Base glass (Li)xPySz,0<x<3,0<y<3,0<z<7) E.g. LiI-Li2S-P2S5Etc.; mixtures thereof and the like; but is not limited thereto.
Further, examples of the inorganic particles having a dielectric constant of 1 or more include SrTiO3、SnO2、CeO2、MgO、NiO、CaO、ZnO、ZrO2、Y2O3、Al2O3、TiO2SiC, mixtures thereof, and the like, but are not limited thereto.
The thermally conductive inorganic particle is a material having an insulating property because it provides low thermal resistance but does not provide electrical conductivity. For example, the thermally conductive inorganic particles may be selected from the group consisting of aluminum nitride (AlN), Boron Nitride (BN), and aluminum oxide (Al)2O3) Silicon carbide (SiC), and beryllium oxide (BeO), but is not limited thereto.
If the above-mentioned high dielectric inorganic particles, inorganic particles having piezoelectricity, heat conductive inorganic particles, and inorganic particles having lithium ion transferring ability are mixed, their synergistic effect can be doubled.
The size of the inorganic particles is not limited, but if possible, it is preferably 0.001 to 10 μm in size in order to form an insulating film having a uniform thickness and to form a suitable porosity between the inorganic particles. If the size is less than 0.001 μm, dispersibility deteriorates, and thus it becomes difficult to control the properties of the organic-inorganic hybrid film. If the size is more than 10 μm, the thickness increases to deteriorate mechanical properties, and the insulating film cannot exert its effect due to an excessively large pore diameter, and the chance of causing an internal short circuit at the time of charge and discharge of the battery increases.
The content of the inorganic particles is not particularly limited, but it is preferable that the content is 1 to 99% by weight, more preferably 10 to 95% by weight, based on 100% by weight of the mixture of the inorganic particles and the binder polymer. If the content thereof is less than 1 wt%, the content of the polymer becomes excessively large to reduce the pore size and porosity due to the reduction of the voids formed between the inorganic particles, and thus the mobility of lithium ions may be deteriorated. On the contrary, if the content thereof is more than 99 wt%, the content of the polymer becomes too small, thereby causing deterioration of mechanical properties of the final insulating film due to weakening of adhesive strength between inorganic materials.
In this way, when the insulating film is formed with an organic-inorganic hybrid film containing a binder polymer and inorganic particles, the insulating film has a uniform pore structure formed by interstitial volumes between the inorganic particles. Through such pores, lithium ions smoothly move, and a large amount of electrolyte is filled to exhibit a high impregnation rate, thereby preventing a reduction in battery performance caused by the formation of an insulating film.
At this time, the pore size and porosity can be controlled together by adjusting the size and content of the inorganic particles.
In addition, the organic-inorganic hybrid film including the inorganic particles and the binder polymer does not have heat shrinkage at high temperature due to heat resistance of the inorganic particles. Therefore, the insulating film is maintained even under stress conditions caused by internal or external factors (e.g., high temperature, external impact, etc.), thereby effectively preventing short circuits and delaying thermal runaway caused by the endothermic effect of the inorganic particles.
Further, such an insulating film may also function as an artificial SEI, thereby also having an effect of suppressing gas generation by suppressing side reactions of the electrolyte.
The thickness of such an insulating film formed may be, for example, 0.1 μm to 50 μm, particularly 1 μm or more, 2 μm or more, or 3 μm or more, and may be 40 μm or less, 30 μm or less, or 20 μm or less.
If the thickness of the insulating film is below the above range, the effect of preventing short circuits may not be achieved. If the thickness thereof is too high, the total volume of the electrode becomes large and the mobility of lithium ions deteriorates, which is not preferable.
Meanwhile, the insulating film may be formed on one side or both sides of the electrode facing the direction of the counter electrode. Therefore, when the counter electrode is laminated on both sides of the electrode, an insulating film may be formed on the entire surface of both sides, or each of the electrode and the counter electrode may include the insulating film.
That is, in one example, an insulating film may also be formed on the entire surface of the counter electrode facing the direction of the electrode, wherein the insulating film may be an organic-inorganic mixed film including inorganic particles and a binder polymer, as in the insulating film formed on the electrode.
For example, when one electrode and one counter electrode are included, an insulating film of the electrode is formed on one side or both sides facing the counter electrode, and the counter electrode may or may not include the insulating film.
However, when more than two electrodes and more than two counter electrodes are included, more different structures are possible.
For example, when two or more electrodes include an insulating film on only one side, one or more counter electrodes may include an insulating film such that the insulating film is formed between the counter electrode and the electrode on the other side of the electrode.
On the other hand, when two or more electrodes include an insulating film on both sides, the counter electrode may or may not include an insulating film.
In addition, when some of the two or more electrodes include an insulating film on only one side and some include insulating films on both sides, various structures are possible. For example, the counter electrode may include an insulating film at a position where there is no insulating film between the electrode and the counter electrode, or the counter electrode may include an insulating film on the entire surface of one side or both sides.
That is, as long as a structure has an insulating film on an electrode and/or a counter electrode at a position where a short circuit may occur between the electrode and the counter electrode, the structure is included in the scope of the present invention.
After intensive studies by the present applicant, it has been confirmed that when the insulator formed on the entire electrode according to the present invention is in the form of an insulating film, it exhibits optimal safety and does not deteriorate the characteristics of the secondary battery, such as capacity, ionic conductivity, and the like. However, when the organic-inorganic hybrid composition is directly coated on an electrode, the secondary battery performance may be degraded, which is not preferable. This is probably because when directly coated, the coating material impregnates into the pores of the electrode mix, thereby increasing the cell resistance.
Therefore, in the present invention, it is named as an insulating film instead of an insulating layer to exclude a coating form.
The insulating film is an insulating film manufactured separately, and may be formed by lamination or transfer on the electrode. Therefore, in the present invention, "formation" of the insulating film includes "lamination" and "transfer".
For clarity, a diagram of the above-described structure of the present invention is shown in fig. 1.
Fig. 1 is an exploded perspective view of an electrode assembly of an embodiment of the present invention, in which an insulating film is formed on an electrode.
Referring to fig. 1, the electrode assembly includes an electrode 100, a counter electrode 120, a separator 110, and an insulating film 130 between the electrode 100 and the separator 110 covering the entire surface 101 of the electrode 100 and a portion of a tab 102.
Meanwhile, in the present invention, the electrode may be a positive electrode or a negative electrode.
For example, when the electrode is a positive electrode, the counter electrode may be a negative electrode, and when the electrode is a negative electrode, the counter electrode may be a positive electrode.
When the electrode is a positive electrode or a negative electrode, the electrode may have a structure in which an electrode mixture including an electrode active material, a conductive material, and a binder is formed on at least one side of an electrode current collector. The counter electrode may have a similar structure in which an electrode mixture including an electrode active material, a conductive material, and a binder is formed on at least one side of an electrode current collector.
Alternatively, when the electrode of the present invention is a positive electrode, the electrode may have a structure in which an electrode mixture including an electrode active material, a conductive material, and a binder is formed on at least one side of an electrode current collector. The counter electrode, which is a negative electrode, may have a structure in which lithium metal is deposited on an electrode current collector, or may be formed of only the electrode current collector.
Alternatively, when the electrode of the present invention is a negative electrode, the electrode may have a structure in which lithium metal is deposited on an electrode current collector, or may be formed of only the electrode current collector. The counter electrode as the positive electrode may have a structure in which an electrode mixture including an electrode active material, a conductive material, and a binder is formed on at least one side of an electrode current collector.
That is, a lithium ion battery, a lithium polymer battery, and the like may be prepared from the electrode assembly of the present invention, but a lithium metal battery using lithium metal as an anode active material, a lithium-free battery made only of an anode current collector, and the like may also be prepared.
Meanwhile, an electrode active material included in the positive electrode is referred to as a positive electrode active material, and an electrode current collector is referred to as a positive electrode current collector.
The positive electrode collector is generally manufactured to have a thickness of 3 to 500 μm, which is not particularly limited as long as such collector has high conductivity while not causing chemical changes of the battery. For example, the current collector used is one selected from stainless steel, aluminum, nickel, titanium, or aluminum or stainless steel surface-treated with carbon, nickel, titanium or silver, particularly aluminum. The current collector may increase the adhesive strength of the positive electrode active material in such a manner that fine asperities are formed on the surface thereof, and may have various forms, such as a film, a sheet, a foil, a mesh, a porous body, a foam, a nonwoven fabric body, and the like.
The positive electrode active material may include, for example, a layered compound or a compound substituted with one or more transition metals, such as lithium nickel oxide (LiNiO)2) Etc.; lithium manganese oxides, e.g. of formula Li1+xMn2-xO4(wherein x is 0 to 0.33), LiMnO3、LiMn2O3、LiMnO2Etc.; lithium-copper oxide (Li)2CuO2) (ii) a Vanadium oxides, e.g. LiV3O8、LiV3O4、V2O5、Cu2V2O7Etc.; from the formula LiNi1-xMxO2(wherein M is Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x is 0.01 to 0.3) or a nickel oxide(ii) a Lithium manganese complex oxide of the formula LiMn2-xMxO2(wherein M is Co, Ni, Fe, Cr, Zn or Ta, and x is 0.01 to 0.1) or Li2Mn3MO8(wherein M ═ Fe, Co, Ni, Cu, or Zn); LiMn2O4Wherein a portion of Li of the formula is substituted with an alkaline earth metal ion; a disulfide compound; fe2(MoO4)3But is not limited thereto.
Similarly, the electrode active material contained in the anode is referred to as an anode active material, and the electrode current collector is referred to as an anode current collector.
Generally, the negative current collector is fabricated to have a thickness of 3 to 500 μm. Such a negative electrode collector is not particularly limited as long as it has conductivity without causing chemical changes of the battery. For example, the current collector used may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloy, or the like. In addition, the negative electrode current collector may increase the binding force of the negative electrode active material in such a manner that the fine irregularities are formed on the surface thereof, and may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven fabric body, and the like, as in the above-described positive electrode current collector.
Since the lithium metal battery may also be manufactured in a form in which the lithium metal itself may simultaneously function as a current collector and an active material, the current collector may use the lithium metal.
As the anode active material, the following can be used: for example, carbon such as non-graphitizing carbon, graphite-based carbon, and the like; metal complex oxides such as LixFe2O3(0≤x≤1)，LixWO2(0≤x≤1)，SnxMe1-xMe’yOz(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of groups 1,2 and 3 of the periodic table, halogen; x is more than 0 and less than or equal to 1; y is more than or equal to 1 and less than or equal to 3; z is more than or equal to 1 and less than or equal to 8), etc.; lithium metal; a lithium alloy; a silicon-based alloy; a tin-based alloy; metal oxides, e.g. SnO, SnO2、PbO、PbO2、Pb2O3、Pb3O4、Sb2O3、Sb2O4、Sb2O5、GeO、GeO2、Bi2O3、Bi2O4、Bi2O5Etc.; conductive polymers such as polyacetylene and the like; Li-Co-Ni based materials, and the like.
The conductive material is generally added in an amount of 0.1 to 30 wt%, preferably 1 to 10 wt%, more preferably 1 to 5 wt%, based on the total weight of the mixture containing the cathode active material. Such a conductive material is not particularly limited as long as it has conductivity while not causing chemical changes of the battery, wherein the following materials may be used: for example, graphite such as natural graphite, artificial graphite, and the like; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc.; conductive fibers such as carbon fibers, metal fibers, and the like; metal powders such as fluorocarbon, aluminum, nickel powders, and the like; conductive whiskers such as zinc oxide, potassium titanate, and the like; conductive metal oxides such as titanium oxide and the like; polyphenylene derivatives, Carbon Nanotubes (CNTs), and the like.
The binder is a component that contributes to adhesion of the active material, the conductive material, and the like, and adhesion to the current collector, and is added in an amount of usually 0.1 to 30% by weight, preferably 1 to 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the mixture containing the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-olefin terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, various copolymers, and the like.
Further, after intensive studies by the present applicant, it has been confirmed that, when an electrode has a structure in which an electrode mixture including an electrode active material, a conductive material and a binder is formed on at least one side of an electrode current collector, and Carbon Nanotubes (CNTs) are included as the conductive material, by including (c) thermally conductive inorganic particles as the inorganic particles in an insulating film, needle-punching safety can be achieved.
That is, when CNT is included as a conductive material, high needle-punching safety can be achieved using an insulating film including thermally conductive inorganic particles as compared to an insulating film including other inorganic particles.
Therefore, when CNT is included as a conductive material, an insulating film including thermally conductive inorganic particles is preferably formed on the surface of the electrode.
Here, the thermally conductive inorganic particles are as described above.
Meanwhile, as a separator interposed between the positive electrode and the negative electrode, an insulating film having high ion permeability and mechanical strength is used. The pore size of the separator is usually 0.01 to 10 μm, and the thickness thereof is usually 1 to 300 μm. As the separator, the following materials can be used: for example, olefin-based polymers such as chemical resistant and hydrophobic polypropylene, and the like; a sheet or nonwoven fabric made of glass fiber, polyethylene, or the like; and so on. If a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also be used as the separator.
In particular, the membrane may be an SRS (safety enhancing membrane) membrane. The SRS diaphragm has the following structure: wherein the organic/inorganic composite porous coating is coated on the base material of the polyolefin-based separator.
The inorganic particles and binder polymer forming the organic/inorganic composite porous coating of the SRS separator are similar to those described above, and the contents thereof are disclosed in KR application No.10-2009-0018123 of the present applicant, which is incorporated herein by reference.
When the separator is an SRS separator, the separator has the same or similar composition as the insulating film, and thus it can be seen that the structures overlap. However, the insulating film formed on the electrode is manufactured and formed separately from the separator and is separated by the boundary of the organic/inorganic composite porous coating layer with the separator.
The conventional battery including the SRS separator still has the above-described safety problem in that lithium dendrites penetrate the organic-inorganic hybrid layer of the SRS separator. Therefore, the insulating film of the electrode should be separated from the SRS separator with a certain boundary to effectively prevent the short circuit of the battery contemplated by the present invention and to ensure the safety of the battery.
More specifically, when there is an insulating film separated from the SRS separator, even if lithium dendrites generated from the negative electrode vertically grow through the SRS separator, the dendrites horizontally grow into a space between the insulating film and the separated SRS separator, thereby preventing a battery from being short-circuited.
According to another embodiment of the present invention, there is provided a method of manufacturing an electrode assembly, including the steps of:
(a) manufacturing an electrode and a counter electrode;
(b) preparing a laminate in which an organic-inorganic hybrid film is laminated on a release film by coating an organic-inorganic hybrid composition containing inorganic particles and a binder polymer on the release film and then drying;
(c) after removing the release film from the laminate, laminating the organic-inorganic mixed film on the entire surface of the electrode facing the direction of the counter electrode, or directly transferring the organic-inorganic mixed film from the laminate to the entire surface facing the direction of the counter electrode to form an insulating film on the electrode; and
(d) the electrode assembly is manufactured by inserting an SRS separator between the electrode on which the insulating film is formed and the counter electrode.
The electrode and the counter electrode of the step (a) may be manufactured to have the above-described structure.
In the step (b), the laminate is formed by coating the release film with the organic-inorganic hybrid composition and drying the coating, wherein the coating thickness of the organic-inorganic hybrid composition may be controlled to correspond to the thickness of the insulating film. The drying is performed in order to evaporate the solvent used for preparing the organic-inorganic hybrid composition, and may be performed at 70 ℃ to 120 ℃ for 5 minutes to 2 hours.
The preparation of the organic-inorganic hybrid composition is similar to that of the organic/inorganic composite porous coating layer of the SRS separator, and the contents thereof may be referred to.
The lamination in the step (c) is a step of first peeling off the organic-inorganic hybrid film from the release film and separately laminating it on the electrode. At this time, lamination may be performed by a method such as crimping, adhesion, or the like.
The transfer in the step (c) refers to a step of directly transferring only the organic-inorganic hybrid film onto the electrode from the release film on which the organic-inorganic hybrid film is formed. The transfer may be performed by rolling or by heating. The above-mentioned transfer may be performed by stacking the stack and the electrode such that the organic-inorganic mixed film faces the electrode, and then rolling or applying heat to transfer the organic-inorganic mixed film from the stack to the electrode.
The process (d) is the same as a general method of manufacturing an electrode assembly known in the prior art.
According to another embodiment of the present invention, there is provided a lithium secondary battery including the electrode assembly and an electrolyte.
As the electrolyte, a nonaqueous electrolytic solution containing a lithium salt is generally used, and the nonaqueous electrolytic solution includes a nonaqueous electrolytic solution and a lithium salt. As the nonaqueous electrolytic solution, the following can be used: non-aqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, and the like, but are not limited thereto.
As the non-aqueous organic solvent, the following aprotic organic solvents can be used: for example, N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ -butyrolactone, 1, 2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1, 3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphotriester, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1, 3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ether, methyl propionate, ethyl propionate, and the like, but is not limited thereto.
As the organic solid electrolyte, the following substances may be used: for example, polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polystirred lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionically dissociable groups, and the like.
As inorganicAs the solid electrolyte, the following substances can be used: e.g. nitrides, halides, sulfates, etc. of Li, e.g. Li3N、LiI、Li5NI2、Li3N-LiI-LiOH、LiSiO4、LiSiO4-LiI-LiOH、Li2SiS3、Li4SiO4、Li4SiO4-LiI-LiOH、Li3PO4-Li2S-SiS2And the like.
As the lithium salt, the following can be used as a material that can be well dissolved in the nonaqueous electrolyte: for example LiCl, LiBr, LiI, LiClO4、LiBF4、LiB10Cl10、LiPF6、LiCF3SO3、LiCF3CO2、LiAsF6、LiSbF6、LiAlCl4、CH3SO3Li、CF3SO3Li、(CF3SO2)2NLi, chloroborane lithium, lower aliphatic lithium carbonate, lithium tetraphenylborate, lithium imide, and the like.
Further, in order to improve charge and discharge characteristics, flame retardancy, and the like, the following may be added to the nonaqueous electrolytic solution: for example, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, N-glyme, hexaphosphoric triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, aluminum trichloride, and the like. In some cases, a halogen-containing solvent such as carbon tetrachloride, trifluoroethylene, and the like may be further contained therein to provide incombustibility, carbon dioxide gas may also be contained therein to improve high-temperature storage characteristics, and FEC (fluoroethylene carbonate), PRS (propylene sulfonate lactone), and the like may also be further included.
As described above, the lithium secondary battery of the present invention may be a lithium ion battery, a lithium polymer battery, a lithium metal battery, or a lithium-free battery.
At this time, lithium metal batteries and lithium-free batteries are particularly apt to form lithium dendrites, and thus are suitable for use in the present invention, and are more suitable when the electrode of the present invention is included.
Such a lithium secondary battery can be used as a power source of a device. The device may be, for example, a laptop computer, a netbook, a tablet, a mobile phone, an MP3, a wearable electronic device, an electric tool, an Electric Vehicle (EV), a Hybrid Electric Vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an electric bicycle, an electric scooter, an electric golf cart, or an electric power storage system, but is not limited thereto.
Drawings
Fig. 1 is an exploded perspective view of an electrode, a separator, and a counter electrode of an embodiment of the present invention.
Detailed Description
Hereinafter, the present invention will be described in detail with reference to the following examples. However, these examples are provided only for better understanding of the present invention, and thus the scope of the present invention is not limited thereto.
< preparation example 1> (organic layer)
Polyvinylidene fluoride-chlorotrifluoroethylene copolymer (PVdF-CTFE) was added to acetone in an amount of about 5 wt%, and dissolved at a temperature of 50 ℃ for about 12 hours, thereby preparing a polymer solution.
< production example 2> (organic-inorganic hybrid layer for coating)
BaTiO was added to the polymer solution of preparation example 13Powder to BaTiO3(PVdF-CTFE: 90/10 wt.%) and ball milling the BaTiO3The powder was crushed and ground for more than 12 hours to prepare an organic-inorganic hybrid composition. BaTiO 23The particle diameter of (b) may be controlled depending on the size (particle diameter) of the beads used in the ball milling method and the time used in the ball milling method. In this preparation example, the BaTiO was added3The powder was pulverized to about 400nm to prepare an organic-inorganic hybrid composition.
< production example 3> (organic-inorganic hybrid film for insulating film)
The organic-inorganic hybrid composition prepared in preparation example 2 was coated on a PET release film in a thickness of 10 μm and dried, thereby preparing a laminate in which the organic-inorganic hybrid film was formed on the release film.
< production example 4> (production of SRS diaphragm)
A polyvinylidene fluoride-chlorotrifluoroethylene copolymer (PVdF-CTFE) polymer was added to acetone in an amount of about 5 wt%, and then dissolved at a temperature of 50 ℃ for about 12 hours to prepare a polymer solution. Adding BaTiO to the polymer solution3Powder to BaTiO3(PVdF-CTFE: 90/10 wt.%) and ball milling the BaTiO3The powder was crushed and ground for 12 hours or more to prepare a slurry. The particle size of the slurry prepared as above may be controlled according to the size of the beads (particle size) used in the ball milling method and the time used in the ball milling method. In this example 1, the BaTiO was added3The powder was pulverized to about 400nm to prepare a slurry. The slurry prepared as above was coated on a polyethylene separator having a thickness of about 18 μm (porosity of 45%) by using a dip coating method, and the thickness of the coating layer was adjusted to about 3.5 μm. The resulting separator was dried at 60 ℃ to form an active layer. The porosity was measured by a porosimeter, and as a result, the size of pores in the active layer coated on the polyethylene separator and the porosity were 0.5 μm and 58%, respectively.
< example 1>
Will have a composition of 95 wt% of a positive electrode active material (LiNi)0.6Co0.2Mn0.2O2) A positive electrode mixture of 2.5 wt% of Super-P (conductive material) and 2.5 wt% of PVDF (binder) was added to a solvent, i.e., NMP (N-methyl-2-pyrrolidone), to prepare a positive electrode slurry, which was then coated (100 μm) on an aluminum current collector, and an aluminum tab was then welded to the uncoated portion of the current collector to prepare a positive electrode.
A negative electrode slurry was prepared by adding a negative electrode mixture of 85 wt% of a negative electrode active material (artificial graphite: MCMB), 10 wt% of Super-P (conductive material), 5 wt% of PVDF (binder) to NMP (solvent). Then, the slurry was coated (100 μm) on a copper current collector, and then a copper tab was welded to the uncoated portion of the current collector to prepare a negative electrode.
The positive electrode was prepared such that the size of the portion other than the tab was 3.0 × 4.5 cm. The anode was prepared so that the size of the portion other than the tab was 3.1 × 4.6 cm. Using the laminate of preparation example 3, the organic-inorganic hybrid film was transferred to a portion other than the tab of the negative electrode, thereby forming an insulating film.
The transfer is performed by laminating the laminate so that the organic-inorganic mixed film faces the portion other than the tab of the negative electrode, and then rolling it with a roll press.
The SRS separator obtained from preparation example 4 was interposed between a positive electrode and a negative electrode to prepare an electrode assembly (bicell), after which the electrode assembly was inserted into a pouch-type case and electrode leads were connected thereto. Then, 4M LiPF will be dissolved6Is injected as an electrolyte, and then sealed to assemble a lithium secondary battery.
< example 2>
A lithium secondary battery was assembled in the same manner as in example 1, except that an insulating film was formed by transferring an organic-inorganic hybrid film to a portion other than a tab of a positive electrode (not a negative electrode) using the laminate of preparation example 3.
< example 3>
A lithium secondary battery was assembled in the same manner as in example 1, except that an insulating film was formed by transferring an organic-inorganic hybrid film onto a portion of an anode including a tab using the laminate of preparation example 3.
< example 4>
A lithium secondary battery was assembled in the same manner as in example 1, except that an insulating film was formed by transferring an organic-inorganic hybrid film to a portion of a positive electrode (not a negative electrode) including a tab using the laminate of preparation example 3.
< comparative example 1>
A lithium secondary battery was assembled in the same manner as in example 1, except that an insulating film was not formed on the anode and the cathode.
< comparative example 2>
A lithium secondary battery was assembled in the same manner as in example 2, except that the laminate of preparation example 3 was not used, and an insulating film was formed by coating the organic-inorganic hybrid composition of preparation example 2 at a thickness of 10 μm on a portion other than the tab of the positive electrode and drying at 60 ℃.
< comparative example 3>
A lithium secondary battery was assembled in the same manner as in example 2, except that the laminate of preparation example 3 was not used, and an insulating film was formed by coating the polymer solution of preparation example 1 at a thickness of 10 μm on a portion other than the tab of the positive electrode and drying at 60 ℃.
< comparative example 4>
A lithium secondary battery was assembled in the same manner as in example 1, except that no insulating film was formed on the negative electrode and the positive electrode, and an insulating tape (PET material, 3M, thickness: 30 μ M) was attached only to the tab portion of the positive electrode.
< Experimental example 1>
In order to determine the safety of the lithium secondary batteries manufactured in examples 1 to 4 and comparative examples 1 to 4, the amount of gas generation at 200 cycles and the voltage drop phenomenon occurring when a short circuit occurred were determined while life evaluation was performed at a high temperature (45 ℃).
The life evaluation was performed by repeating charging and discharging at 1.0C for 500 cycles in the interval of 2.5 to 4.35V.
The results are shown in table 1 below.
TABLE 1
Figure BDA0002650382910000151
Referring to table 1, it was confirmed that in the case of forming the insulating film according to the present invention, the generation amount of gas was reduced by reducing the oxidation/reduction decomposition of the electrolyte, and also the internal short circuit caused by lithium dendrite was reduced.
However, when an insulating film is not formed on the tab portion of the positive electrode due to the difference in the areas of the positive electrode and the negative electrode (example 2), a part of the positive electrode tab faces the negative electrode, and thus a short circuit may occur. Therefore, it is more preferable to form the insulating film to the tab portion.
On the other hand, in comparative example 1 in which no insulating film was formed or comparative example 4 in which only an insulating tape was attached to the tab piece, it was confirmed that a large amount of gas was generated and the internal short circuit could not be effectively prevented. Comparative examples 2 and 3 seem to be effective in suppressing short circuits and reducing the amount of gas generated, but are not as structured as the present invention, and there is a problem that the secondary battery performance is lowered, as shown in the following experiments.
< comparative example 5>
A lithium secondary battery was assembled in the same manner as in example 2, except that an insulating layer was formed by coating the organic-inorganic hybrid composition of preparation example 2 at a thickness of 10 μm on a portion except for a tab of a positive electrode and drying at 60 ℃, and then an insulating film was formed by coating the polymer solution of preparation example 1 at a thickness of 10 μm and drying at 60 ℃.
< Experimental example 2>
The lithium secondary batteries prepared in example 2 and comparative examples 2, 3, 4 and 5 were subjected to three times of charge and discharge at 0.1C, and then to three times of charge at 0.1C and discharge at 2C in an interval of 2.5V to 4.5V to obtain an average discharge capacity of 2C/an average discharge capacity of 0.1C in%. The results are shown in table 2 below.
TABLE 2
Capacity retention (%)
Example 2 93
Comparative example 2 65
Comparative example 3 55
Comparative example 4 78
Comparative example 5 70
Referring to table 2, when the insulating film of the present invention was used, the capacity was hardly decreased. However, when an insulating layer in the form of a coating layer was formed instead of the insulating film (comparative examples 2 and 3), and when only an insulating tape was attached to the positive electrode tab (comparative example 4), the capacity was decreased. In addition, even when the organic-inorganic insulating layer and the organic layer are used together, the resistance increases, thereby decreasing the capacity retention rate.
< Experimental example 3>
In order to confirm the improvement of safety, the lithium secondary batteries prepared in example 3 and comparative examples 1 and 3 were subjected to a hot box test while being heated from 130 ℃ at a rate of 5 ℃/min for 1 hour. The results are shown in table 3 below.
TABLE 3
Detonation temperature (. degree.C.)
Example 3 197
Comparative example 1 178
Comparative example 3 180
Referring to table 3, when the insulating film of the present invention was formed, it could withstand higher temperature than the case where the insulating film was not formed (comparative example 1), the case where the polymer insulating layer was formed (comparative example 3), and the case where the organic layer was used (comparative example 3), thereby exhibiting excellent safety.
< example 5>
A positive electrode was prepared in the same manner as in example 1, except that Carbon Nanotubes (CNTs) were used as a conductive material in preparing the positive electrode.
An anode was prepared in the same manner as in example 1.
The positive electrode was prepared such that the size of the portion other than the tab was 3.0 × 4.5 cm. The negative electrode was prepared so that the size of the portion other than the tab was 3.1 × 4.6 cm. Using the laminate of preparation example 3, an insulating film was formed by transferring an organic-inorganic hybrid film to a portion of the positive electrode including the tab.
The transfer is performed by laminating the laminate so that the organic-inorganic mixed film faces the portion other than the tab of the negative electrode, and then rolling it with a roll press.
The SRS separator obtained from preparation example 4 was interposed between a positive electrode and a negative electrode to prepare an electrode assembly (bicell), after which the electrode assembly was inserted into a pouch-type case and electrode leads were connected thereto. Then, 4M LiPF will be dissolved6Is injected as an electrolyte, and then sealed to assemble a lithium secondary battery.
< preparation example 5>
To the polymer solution of preparation example 1, AlN (aluminum nitride) powder was added so as to attain AlN/PVdF-CTFE of 90/10 (wt% ratio), and then, the resultant AlN powder was crushed and ground by a ball milling method for 12 hours or more, thereby preparing an organic-inorganic hybrid composition. The particle size of AlN may be controlled according to the size (particle size) of the beads used in the ball milling method and the time for the ball milling method. In this preparation example, the AlN powder was pulverized at about 400nm to prepare an organic-inorganic hybrid composition. The organic-inorganic hybrid composition thus prepared was coated on a PET release film and dried to prepare a laminate in which the organic-inorganic hybrid film was formed on the release film.
< example 6>
A lithium secondary battery was assembled in the same manner as in example 5, except that a positive electrode and a negative electrode were prepared as in example 5, but an insulating film was formed by transferring an organic-inorganic hybrid film onto a portion of the positive electrode including a tab, using the laminate of preparation 5.
< comparative example 6>
A lithium secondary battery was assembled in the same manner as in example 5, except that the positive electrode and the negative electrode were prepared as in example 5, but no insulating film was formed on the positive electrode and the negative electrode.
< Experimental example 4>
In order to confirm the improvement of safety, the lithium secondary batteries prepared in examples 4 to 6 and comparative examples 1 and 6 were subjected to a needle punching test at 6m/min using a needle having a diameter of 25mm, and the results are shown in table 4 below. The case where fire did not occur when the needle pricked was recognized as "pass", and the case where fire occurred was recognized as "fail".
TABLE 4
Number of passages/number of evaluations
Example 4 5/5
Example 5 3/5
Example 6 5/5
Comparative example 1 3/5
Comparative example 6 0/5
Referring to table 4, in the case of not containing CNT as a conductive material (example 4), the needle-punching safety was excellent even with an insulating film of any inorganic particles. However, in the case of containing CNTs as a conductive material (examples 5 and 6), the needle-punching safety can be ensured only when using thermally conductive inorganic particles as the inorganic particles, otherwise the safety is lowered to some extent.
On the other hand, when the insulating film is not formed, safety is lowered in any case. In particular, when CNTs were used as the conductive material, it was confirmed that the safety was greatly lowered.
It should be understood that various applications and modifications within the scope of the present invention may be made by those skilled in the art to which the invention pertains, based on the above description.
Industrial applicability
As described above, the electrode assembly of the present invention can prevent a short circuit between electrodes caused by an internal/external short circuit, a partial compression, etc. by including an insulating film on the entire surface of one or both sides.
In addition, since the electrode assembly of the present invention includes the organic-inorganic hybrid film on the surface of the electrode, it may be used as an artificial SEI to suppress side reactions of the electrolyte that may be caused by contact between the electrode material and the electrolyte. Therefore, the battery safety can be improved by suppressing gas generation, and lithium ions can move, thereby preventing a decrease in capacity and output characteristics.
In addition, since the present invention forms an insulating film on the surface of the electrode alone, not in the form of a coating layer, it is possible to prevent degradation of battery performance that may occur when a coating material is incorporated into pores of the surface of the electrode.
Further, the insulating film included in the electrode assembly of the present invention includes a specific inorganic material, and the inorganic material has a heat absorption effect, thereby delaying thermal runaway.

Claims (15)

1. An electrode assembly for a lithium secondary battery, comprising an electrode, a separator and a counter electrode,
wherein an insulating film is formed on the entire surface of one or both sides of the electrode, and the insulating film is an organic-inorganic hybrid film containing inorganic particles and a binder polymer.
2. The electrode assembly according to claim 1, wherein the electrode includes a tab extending from a current collector, and the insulating film is further formed on the tab.
3. The electrode assembly according to claim 1, wherein the inorganic particles are at least one selected from the group consisting of (a) inorganic particles having a dielectric constant of 1 or more, (b) inorganic particles having piezoelectricity, (c) thermally conductive inorganic particles, and (d) inorganic particles having lithium ion transferring ability.
4. The electrode assembly according to claim 1, wherein the binder polymer is at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-vinyl acetate copolymer, polyimide, polyethylene oxide, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullan, cyanoethylpolyvinyl alcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxymethyl cellulose, and polyvinyl alcohol.
5. The electrode assembly according to claim 1, wherein the inorganic particles are contained in an amount of 1 to 99 wt% based on 100 wt% of the mixture of the inorganic particles and the binder polymer.
6. The electrode assembly according to claim 1 or claim 2, wherein the insulating film has a thickness of 0.1 μm to 50 μm.
7. The electrode assembly according to claim 1, wherein the insulating film is formed on the entire electrode surface facing the direction of the counter electrode.
8. The electrode assembly according to claim 1, wherein the insulating film is formed on the entire surface of the counter electrode facing the direction of the electrode, and the insulating film is an organic-inorganic hybrid film containing inorganic particles and a binder polymer.
9. The electrode assembly of claim 1, wherein the electrode is a positive electrode and the counter electrode is a negative electrode.
10. The electrode assembly of claim 1, wherein the electrode is a negative electrode and the counter electrode is a positive electrode.
11. The electrode assembly according to claim 1, wherein the electrode has a structure in which an electrode mixture containing an electrode active material, a conductive material and a binder is formed on at least one side of an electrode current collector and Carbon Nanotubes (CNTs) are included as the conductive material, and the insulating film includes (c) thermally conductive inorganic particles as the inorganic particles.
12. The electrode assembly according to claim 11, wherein the (c) thermally conductive inorganic particles are selected from the group consisting of aluminum nitride (AlN), Boron Nitride (BN), and aluminum oxide (Al)2O3) Silicon carbide (SiC) and beryllium oxide (BeO).
13. The electrode assembly of claim 1, wherein the separator is an SRS separator.
14. A method of manufacturing the electrode assembly of claim 1, comprising the steps of:
(a) manufacturing an electrode and a counter electrode;
(b) preparing a laminate in which an organic-inorganic hybrid film is laminated on a release film by coating an organic-inorganic hybrid composition containing inorganic particles and a binder polymer on the release film and then drying;
(c) after removing the release film from the laminate, laminating the organic-inorganic mixed film on the entire surface of the electrode facing the direction of the counter electrode, or directly transferring the organic-inorganic mixed film from the laminate to the entire surface facing the direction of the counter electrode, thereby forming an insulating film on the electrode; and
(d) the electrode assembly is manufactured by inserting an SRS separator between the electrode having the insulating film formed thereon and the counter electrode.
15. A lithium secondary battery comprising the electrode assembly of claim 1 and an electrolyte.
CN202080001682.1A 2019-02-01 2020-01-31 Electrode assembly having insulating film, method of manufacturing the same, and lithium secondary battery including the same Pending CN111801839A (en)

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